visualtheme.css

/*highlight the small rows*/
.main-layout > div:nth-child(4n-1), .main-layout > div:nth-child(4n) {
    background: #777
}

.main-layout > div {
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 5px;
    background-color: #AAA;
    color: white;
    font-size: 32px;
}

@media (min-width: 768px) {
        .main-layout > div:nth-child(4n-1), .main-layout > div:nth-child(4n) {
            background: #777
        }
}    

@media (max-width: 767.98px) {
    .main-layout > div:nth-child(odd) {
        background: #777
    }
}